1. Field Of Invention
This invention relates to disposable wipers having multiple purposes and applications in both industrial and consumer industries. While there are a variety of applications it is particularly useful for industrial, institutional and health care heavy duty wiping uses where textile wiping materials and some nonwoven and natural fiber wipers are traditionally used. Such wipers must have excellent strength and absorbency performance characteristics, soft handfeel, bulk, conformity and of overall durability to be reused if desired. While some textile wiping materials and some disposable nonwovens possess some of the desired characteristics, they may be restricted in use due to the nature of their embodiments or, as is the case with some nonwovens, by adverse characteristics resulting from the method of material manufacture or material web laminating such as with adhesives, hot embossing or autogenous bonding. It is therefore desirable to improve the presence of all the performance characteristics as a combination, particularly strength and absorbency, by way of a wipe material that is softer with more bulk and conformity than many textile and nonwoven wiping materials and at a cost that is traditionally lower than textile wipers and many nonwoven wipers.
2. Description Of Prior Art
U.S. Pat. No. 3,837,995 to J. Floden issued Sept. 24, 1974 describes a autogenously bonded nonwoven web consisting of one or more layers of synthetic, thermoplastic polymeric microfibers and one or more layers of natural fibers bonded by layer contact when drawn through or over machine rollers. Supplemental bonding may be required between the natural fiber layers when multi plies of natural fibers are used. This wiper laminate is said to have a softer handfeel than wiper laminates of composite webs having been supplementaly bonded by adhesives or by hot embossing. This wiper laminate is useful for limited applications where bond strength requirements are normally 1.5 g/cm(-).
U.S. Pat. No. 3,870,592 to R. Brock issued Mar. 11, 1975 describes a laminate comprised of outer webs of continuous thermoplastic filaments and an inner web of cellulose wadding. Composite layer bonding is accomplished by applying a piastisol adhesive to the cellulose web which is then brought in contact with the continuous filament webs through rollers and then passed over a heated drum for curing. While recognizing that supplemental bonding has a adverse effect on some laminate characteristics such as softness and absorbency, this laminate did provide improved hand feel and absorbency over a web of continuous thermoplastic filament alone.
U.S. Pat. No. 3,695,985 to R. Brock issued Oct. 3, 1972 describes a hight bulk laminate with continuous thermoplastic polymer filament inner layer and outer layers of cellulosic web. The composite layers are supplemental-bonded by adhesives to set the cellulose webs with the continuous filament web and then hot embossed as a second step to set the laminated web into a predetermined pattern. This composite laminate relates to nonwoven disposable materials, particularly those utilized for toweling, and exhibits improved bulk, absorbency and resiliency over traditional nonwoven disposable toweling at that time. As referenced in the aforementioned prior art, this method of supplemental web bonding usually adversely effects softness and absorbency and may limit the number and variety of uses.
Production per se of continuous thermoplastic filament layers and the manner of formation are not particularly important to this invention and different techniques may be used some of which are set forth in U.S. Pat. Nos. 3,338,992 and 3,341,394 issued to Kinney. Various types of material polymers may also be used to form the continuous filament web while the preferred described herein is polypropylene.
Production per se of natural cellulose fiber layers are not particulaly important to this invention and various fiber types made by conventional wet or dry formed methods may be used.
The manner of stitchbonding the composite wiper web is performed by stitchbonding machines, preferrably Maliwatt machines, as referenced in T. Holiday's "Stitchbonding--Alive and Well" Non-wovens Industry, February 1984 and by Maliwatt and Malimo stitching and knitting machines descriptive literature.